Influence of bioinspired riblet topographies on the mitigation of flow-induced noise in towed sonar arrays

The hydrodynamic optimization of marine vehicles and devices is a critical area of research, especially regarding the diminution of flow-induced drag pertinent to towed sonar arrays. The utilization of bio-inspired riblets, which emulate the skin of rapid marine predators such as sharks, has been posited as a viable strategy to mitigate hydrodynamic drag. Nonetheless, the implications of these riblets on the concurrent acoustical emissions during flow-array interaction remain not well understood. This study conducts an in-depth investigation into the performance of bioinspired riblet topologies in attenuating flow-induced noise in towed sonar arrays, scrutinizing their effectiveness across laminar and turbulent flow regimes. In laminar flow regimes, the study observes that riblet structures have the potential to reduce noise but at the cost of increased drag for towed arrays. Conversely, in turbulent flow conditions, the effectiveness of riblets is significantly enhanced. Particularly, rectangular riblets demonstrate a notable reduction in noise by up to 14.3%, along with a 5.1% decrease in hydrodynamic drag, in comparison to a smooth array surface. Additionally, our parametric study reveals that riblets with finer, more closely spaced geometries can further reduce the drag by an additional 25.7%. These findings underscore the efficacy of riblet geometries in different flow conditions, highlighting their potential in optimizing the acoustic and hydrodynamic performance of maritime systems.